Method and Apparatus for Creating and Distributing Cost Telephony-Switching Functionality within an IP Network

ABSTRACT

A system for providing and managing IP telephone calls establishes separate and distinct call legs between IP-capable appliances and routers and between routers, and creates calls, changes calls, and manages telephony functions by joining and disjoining calls legs. In some instances one or more call legs disjoined from an active call are maintained as established to be joined later to other call legs to create other active calls. By managing EP calls as separate and distinct legs functions of intelligent, connection-oriented telephony networks may be simulated in IP telephony systems. The management is provided by software running on processors coupled to routers in the IP network.

BACKGROUND OF THE INVENTION

1. Field of the invention

The present Invention is in the field of telephony communications andpertains more particularly to methods and apparatus for creatingtelephony switching type functionality on an Internet Protocol (IP)network in a distributive fashion.

2. Discussion of the State of the Art

The field of telephony communication has undergone revolutionaryimprovement with the addition of computer integration by way oftelephony-switch-connected digital processors miming softwareapplications designed to improve call processing and switchingintelligence within a communication center and in some cases, within acommunications network Such integration of telephony equipment andcomputer-processing equipment is known in the art ascomputer-telephony-integration (CTI), and is well known and widelyavailable in various forms. Communications centers, as described above,are generally integrated with a connection-orientated-switched-telephony(COST) network such as a public-switch-telephone-network (PSTN) as isknown in the art. In some cases, there are multiple centersinterconnected via a wide-area-network WAN as known in the art.

In typical application, a communication center is enhanced with a CTIprocessor and software adapted to be connected to a communication-centerCOST switch, such as a PBX (central switch) within or local to thecommunication center for the purpose of improving intelligence to theCOST switch by virtue of added software. In some embodiments known tothe inventor, CTI capability is also added to telephony switches withina COST network such as to a service-control-point (SCP). CTI processors(network level and communication center processors) are connectedtogether by a digital link so that certain CTI functions implemented atan SCP may be controlled from within a communication center (known toinventor). In this way intelligent routing, and other CTI functions maybe initiated at network level and communication efficiency may begenerally improved.

Data-network-telephony (DNT) communication has recently been developedfor the purpose of allowing voice/video calls to be placed over a packetdata network. A sub-set of DNT known asInternet-protocol-network-telephony (IPNT) is the most successful andwidely implemented format practiced on data networks such as the wellknown Internet. Communication center capabilities have been furtherimproved via implementation of local area network (LAN) capability,addition of communication equipment such as LAN-connected personalcomputer/video display units (PC/VDU's) with software to implementIP-telephony, and so on.

Agents or other users working in such a CTI-enhanced communicationcenter, or in a large organization hosting multiple communicationscenters, no longer simply answer switch-connected telephones. Access toIP networks have enabled communication centers and multi-center sites toutilize PC/VDU's and other digital apparatus to send and receive e-mailsand voice calls/messages in data-network-telephony (DNT) format.

Communication centers have more recently incorporated IPNT technologiesinto their COST infrastructure. Hence, IP calls as they are termed inthe art, may be placed and received in much the same way as COST calls.In a typical scenario, data-router gateways (nodes) are set-up in an IPnetwork for point-to-point connection between nodes. Nodes local tocommunications centers are connected to telephony switches (usually aPBX) at respective communication centers. Typically, such IP technologyonly replaces switch-to-switch telephony trunking in this scenario.

In true IP telephony, as known to the inventor, traditional COSTswitches at communications centers are replaced by IP-capable switches.Cost functions, such as some PBX features, are emulated at IP switchesby incorporating CTI software to provide intelligent network (IN)functionality. A problem with this approach, however, is that some PBXfunctions cannot be economically practiced with IP telephony. Forexample, if an IP call is placed from one site to a second site, and theuser at the second site is having his calls forwarded to a third partyat the first site, then the call must travel two times across the link.This is due to current art requirements in DNT for setting up eachinstance of connection from source to final destination each time aconnection is needed. Because IP telephony uses shared bandwidth asopposed to having a COST dedicated connection, capacity is wasted withmultiple channel establishment, and quality of service (QoS) associatedwith IP calls over the connection may be degraded if there are many suchcalls. This is true in a COST integrated IP network, as well as in an IN(true IP).

What is clearly needed is a method and apparatus that will emulate PBX,or other standard COST-switch functions and features on an IP network,including connected communication centers, with minimal degradation ofQoS or using up otherwise available resources.

SUMMARY OF THE INVENTION

In a preferred embodiment of the present invention a system forsimulating connection-oriented telephony functions in an IP network isprovided, comprising two or more IP routers interconnected with two ormore call appliances on a network; and software managing setup andexecution of IP calls between call appliances through the routers. Inthe system IP calls are managed by the software by setting up separateand distinct end-node call legs between call appliances and routers, andseparate and distinct intermediate call legs between routers, and thenjoining legs to establish voice communication and to provide telephonyfunctions.

In some embodiments of the system call appliances include InteractiveVoice Response (IVR) units, and the system establishes end-node legsbetween IVRs and IP routers. Also in some embodiments, in providingtelephony functions, call legs once established and joined may bedisjoined and maintained in established state for future use to berejoined to other established call legs. The software executes directlyon one or more IP routers connected to the network, or on one or moreprocessors enhancing IP routers on the network. In some cases there isat least local area network (LAN) connecting end appliances at one ormore of the IP routers, and wherein end-node legs are established viathe LAN to appliances on the LAN.

In another aspect of the invention a method for simulatingconnection-oriented telephony functions in an IP network is provided,comprising steps of (a) interconnecting two or more IP routers with twoor more call appliances on a network; (b) setting up separate anddistinct end-node call legs between call appliances and routers, andseparate and distinct intermediate call legs between routers; and (c)joining and disjoining legs to provide telephony functions.

In the method call appliances may include Interactive Voice Response(IVR) units, and the system establishes end-node legs between IVRs andIP routers. The method may also include steps for disjoining call legsof completed calls and maintaining one or more disjoined legs inestablished state for future use to be rejoined to other establishedcall legs in providing telephony functions. In preferred embodiments thesoftware executes directly on one or more IP routers connected to thenetwork, or on one or more processors enhancing IP routers on thenetwork. There may also be at least one local area network (LAN)connecting end appliances at one or more of the IP routers, and a stepfor establishing end-node legs via the LAN to appliances on the LAN.

In yet another aspect of the invention a method for establishing an IPtelephone call from a first IP-capable appliance through first andsecond IP routers to a second IP-capable appliance, comprising steps of(a) setting up a separate and distinct end-node call leg between thefirst appliance and the first router; (b) setting up a separate anddistinct) end-node call leg between the second appliance and the secondrouter; (c) setting up at least one separate and distinct intermediatecall leg between the first and second IP routers; and (d) joining thecall legs to establish voice communication.

This method for establishing a call may further comprise additionalinterconnected routers and appliances, and may include steps for settingup further call legs to additional appliances and between routers, andfor joining and disjoining call legs to establish voice communication bydifferent paths over established call legs. Some call legs aremaintained after being disjoined from active calls to be used later tobe joined to other call legs to create other active calls. There mayfurther be Interactive Voice Response (IVR) units, and call legs may beestablished to IVRs.

In embodiments of the invention, by setting up separate and distinctcall legs between routers and appliances, and then joining anddisjoining the legs to establish and discontinue voice communication,legs can be joined and disjoined to provide different active calls andto provide intelligent call functions not before available inIP-telephony.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is an overview of an IP communication system emulating a PBXprimitive according to an embodiment of the present invention.

FIG. 2 is a table illustrating several IP/PBX primitives, which may beemulated in the system of FIG. 1 according to an embodiment of thepresent invention.

FIG. 3 is a block diagram illustrating a CTI management link to an IPnetwork according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to a preferred embodiment of the present invention, a methodand apparatus is provided and adapted to emulate and distribute COSTswitching functions within an IP network without use of COST switches,and wherein Intelligent Network capability is enhanced.

FIG. 1 is an overview of an IP communications system 11 emulating a PBXfunctionality according to an embodiment of the present invention. IPcommunications-system 11 comprises in this example three connectedcommunications sites 13, 15, and 17. IP system 11 may, in someembodiments, be integrated with a COST network such as a PSTN network ora private COST network (COST equipment not shown). In other embodiments,EP system 11 may be a company-hosted IP network such as a corporatewide-area-network (WAN) linked to the Internet. There are many possibleand variant architectures that may be implemented with respect to an IPnetwork such as network 11.

Communications sites 13, 15, and 17 may, in one embodiment, becommunications centers. In another embodiment, such sites may becommunication-network hubs linking multiple communication centers orcall-in sites. IP switches 19, 21 and 23 are implemented one each atrespective communication site 13, 15, and 17. IP switch 19 within site13 is linked to IP switch 21 within site 15 via a data-networkconnection 27. IP switch 19 is also connected to IP switch 23 withinsite 17 via a data-network connection 25. Data-network connections 27and 25 are, in this embodiment, integrated-service-digital-network(ISDN) connections. However, other known types of connections may beused provided that at least one voice-communication protocol of thefamily of network protocols known asTransfer-Control-Protocol/Internet-Protocol (TCP/IP) is observed. Onesuch protocol enabling voice communication is H323 IP protocol.

In this example a COST function (call-waiting) is described and emulatedin system 11 without using COST switching apparatus. Furthermore, set-upand execution of the call-waiting feature is performed in a manner thatrequires fewer resource than would otherwise be required in an IPenvironment.

Referring again to FIG. 1, a user A associated with site 13 and havingan IP-capable telephone or other IP-call-capable appliance connected tothe network is engaged in an established call with a user B, also havinga capable phone appliance, associated with site 15. For purposes of thedescriptions herein, it is to be understood that IP calls made by a useror an end-site are made using IP-capable equipment, such as a PC/VDU oran IP-phone or appliance, although it may not be explicitly stated inall instances. An IP-capable appliance is considered the most genericterm, including IP-capable telephones, PCs, IP-capable cell phones,organizers, and the like; that is, any device capable of supporting anIP telephone call.

In the art, such a call is established from one user's equipmentdirectly to the other, as the directing influence will be the IP addressof the called party. In the present invention, however, separate legsare established, identified, and separately maintained, for reasons thatwill quickly become apparent. The separate and unique call legs are setup and manipulated by CTI applications running either on the IP routers(such as router 19), or on CTI servers connected to and enhancing the IProuters. In some cases address translation in the IP routers/switches isused, but other, equivalent strategies are gateways, gatekeepers etc,all either well known or recently introduced into.

There are four call-legs that enable this working connection throughnetwork 11 in this example. An end-node leg A1 is established betweenuser A and switch 19 and is illustrated by arrow A1. An intermediatecall-leg A2 is established between switch 19 within site 13 and switch21 within site 15. Leg A2 is illustrated by arrow A2. These two legs, A1and A2 represent one half of a working connection. The other half of theworking connection comprises an end-node leg B1 that is establishedbetween user B and switch 21 (directional arrow B1), and an intermediateleg B2 which is established between switch 21 and switch 19 (directionalarrow B2). This working connection allows two-way voice communicationusing, in this instance, H323 voice protocol over the ISDN connection.

During the time of the established voice call between user A and user B,a user C associated with site 17 places a call to user A. In aconventional system the call would simply be rejected. In this examplean IVR 29 is provided, and the call is queued in IVR 29 associated withswitch 23 as is consistent with a call-waiting feature. Redirection isaccomplished by CTI applications running on the IP routers or CTIprocessors associated with the IP routers, using address translationtechniques. To illustrate serial active steps performed to affectcompletion of this example, consider the following.

An end-node leg C1 is first established between user C and switch 23(directional arrow C1). Because user A is currently unavailable, and theintelligence associated with IP router 23 discerns this fact through acontrol signal to router 19, a second end-node leg C2 is establishedbetween IVR 29 and switch 23 (directional arrow C2). End-node leg C2 hasattributes of leg C1 for the purpose of call identification andassociation such as QoS, billing responsibility, and other requiredinformation used to associate the two legs. End-node legs C1 and C2 arethen joined resulting in IVR parking of the call from user C. Anintermediate call-leg C3 is then established between switch 23 in site17 and switch 19 in site 13 and maintained in established state inanticipation of call connection. Hence, one-half of a working connectionis set up and a call alert is sent to switch 19 over connection 25, touser A over working end-node leg A1. User A is now notified of animpending call from user C by an agreed alert. In an alternativeembodiment call notification may be sent from switch 23 to switch 19 anduser A over end-node leg A1 without establishing intermediate leg C3 ifa separate (non-voice) control channel is used for such alerting.

At a request from user A, who decides to accept the incoming waitingcall from user C, an end-node leg B3 is established between an IVR 31 atsite 15 to switch 21 (arrow B3). This set up includes attributes ofend-node leg B1 such as QoS, billing responsibility, and other requiredinformation used to associate the two legs. After a connection isestablished by joining legs B1 and B3, (user B queued at IVR 31), legsB2 and A2 (intermediate legs) are disjoined from active voicecommunication, but are maintained in an established state inanticipation of returning to the call from user B (holding).

User A may now pick-up the call from user C as follows. An intermediateleg A3 is set-up between switch 19 in site 13 and switch 23 in site 17over network connection (arrow A3). Leg A3 contains attributes of leg A1for call-association purposes as described above. Leg A1 and A3 arejoined by a function of the associated intelligence at the routers.End-node leg C1 is now joined to intermediate leg C3 according to H323voice protocol. End-node leg C2 is then deleted because it is no longerrequired.

In this example, user A has exercised through unique system capability acall-waiting feature which is a standard COST feature. By manipulatingthe call legs in an ordered fashion specific to each type ofCOST-switch-feature emulated, the IP call does not have to travel as farover the tie-line. More simply, by disjoining call legs but remandingthem in an established state, re-set procedures inherent to prior-art IPnetworks may be avoided. Therefore, the network may handle more callsusing fewer resources, and the calls may be established and routed morequickly than normal. The inventor has discovered that virtually any COSTswitching feature can be made available to IP network 11 through themanipulation of call legs. Also, the exact order of call-legmanipulation will depend largely upon the feature emulated used. Theexample provided above is exemplary of just one such possibility.Several call primitives suggested for emulation of COST functionalityare described more fully below.

FIG. 2 is a table 33 illustrating IP/PBX call primitives, which may beemulated in network 11 of FIG. 1 according to an embodiment of thepresent invention. Table 33 illustrates several primitives or commandsthat may be assembled to provide a feature such as call-waiting, callconsult, call conferencing, and so on. Table 33 assumes that H323 voiceprotocol and ISDN connections are used. However, other protocols andconnections may be used in other embodiments as previously described.

Table 33 has two columns. A left column under the heading Primitivelists each primitive by name. A second column under the headingDescription describes the functions of each primitive listed in thefirst column. Organization of table 33 is such that the description of aprimitive is located immediately to the right of the primitivedescribed. For example, the first-listed entry SETUP involves creatingcall legs according to existing protocol, in this example, H323 voicecommunication over ISDN connection. Attributes of any existing legs tobe joined are also included such as QoS andresource-reservation-protocol (RSVP), caller ID, call destination, andso on.

Working down from SET-UP, Call Proceed involves sending indication ofand responsibility of a call. Call Alert involves sending indication ofcall destination to a target end-node. Call Alert may, in someembodiments, be executed without setting up a completed half of aworking connection such as by exerting command control through an IPback-channel or control channel. Call Connect establishes voicecommunication over completed call architecture (all involved call-legs).Call Reject covers non-acceptance of an incoming call by rejectingestablishment of an incoming call-leg. Call Release drops a call-leg butmaintains it in an established state in anticipation of returning to thecall. Call Join establishes voice communication between call legs suchas with a dropped leg and an existing leg. Call attributes are used toassociate legs as described above. Call Disjoin breaks voicecommunication between call legs with an option to maintain them inestablished state.

Table 33 as illustrated herein is meant to be exemplary only. It will beapparent to one with skill in the art that additional call primitivesnot listed may be included therein without departing from the spirit andscope of the present invention. Organization and manipulation ofindividual call legs to emulate features and send commands is providedvia CTI enhancement modules executed on IP switch-connected processors,or within the IP switch itself. More detail regarding CTI managementarchitecture is provided below.

FIG. 3 is a block diagram illustrating a CTI management link to an IPnetwork according to an embodiment of the present invention. In thisembodiment, two communications sites 35, and 37 are represented. Sites35 and 37 are analogous to sites 13-17 of FIG. 1 and are shown here ascommunications centers. Hereafter, the term communications center willbe used to describe site 35 and site 37.

Communication center 35 comprises an IP switch 39, a local-area-network(LAN) 47, and LAN-connected DNT capable telephones 51 and 53. A CTIprocessor 43 is provided and adapted to provide monitoring and controlservices to switch 39 via a OTT link 42. Communication center 37comprises an IP switch 41, a LAN 49, and LAN-connected DNT telephones55, and 57. A CTI processor 45 is adapted to provide monitoring andcontrol services to switch 41 via a CTI link 44.

Communications centers 35 and 37 are connected to each other by an IPnetwork link 40. In some embodiments, network link 40 may include PSTNnetwork integration as well as integration with other IP networks.Communication centers 35 and 37 are not required to have identicalcommunications equipment or connection apparatus. The fact that they areidentical in this embodiment is only a convenience for description. Theonly requirement is that they are connected to the CTI processingcapability according to an embodiment of the present invention.

The software used to manipulate the call legs as in FIG. 1 and to sendcommands between centers 35 and 37 is implemented on each connectedprocessor 43 and 45. In another embodiment, software capability may beincorporated within each switch 39 and 41 without requiring separateconnected processors such as processors 43 and 45. Communication andcontrol routines are routed through network link 40 with IPcommunication using a voice channel, and other data using a controlchannel. Overall cooperation between separate IP sites is assuredthrough usually continuous communication between the functionintelligences at the various connected sites.

This example illustrates the simple nature of CTI enhancement toswitches 39 and 41. Intermediate call-legs as previously described withreference to FIG. 1 above are set up over network link 40. End-node legsare set up between switches and end-nodes over respective LAN's. Forexample, an end-node leg may be established between switch 39 and DNTphone 51, switch 39 and DNT phone 53 or other connected devices that arecapable of IP communications such as PC/VDU's (not shown). As previouslydescribed, virtually any COST switching function may be emulated onnetwork link 40.

It will be apparent to one with skill in the art that any number ofvarying network architectures may be implemented as network 40 withoutdeparting from the spirit and scope of the present invention. Forexample, communication sites may be in fact communication centers thatare interconnected via an IP network wherein each communication centermaintains an IP switch and CTI processor. In another embodiment, IPswitches may represent communication hubs distributed thoroughout an IPnetwork with communication centers linked locally to each switch.Distributed PBX functionality in an IP network may also includeintegration with other networks both IP and COST. There are many suchpossibilities.

It will further be apparent to one with skill in the art that COSTemulation software running on IP/CTI processors may include or beintegrated with routing and other control routines normally implementedin such processors. The present invention should be afforded thebroadest of scope. The spirit and scope of the present invention islimited only by the claims that follow.

1. A system for simulating connection-oriented telephony functions in anIP network, comprising: two or more IP routers interconnected with twoor more call appliances on the network; and software managing setup andexecution of IP calls between call appliances through the routers;wherein IP calls are managed by the software by setting up separate anddistinct end node legs between call appliances and routers, and separateand distinct intermediate legs between routers, and then joining anddisjoining legs to establish voice communication and to providetelephony functions.
 2. The system of claim 1 wherein call appliancesinclude Interactive Voice Response (IVR) units, and wherein the systemestablishes end-node legs between IVRs and IP routers.
 3. The system ofclaim 1 wherein, in providing telephony functions, call legs onceestablished and joined may be disjoined and maintained in establishedstate for future use to be rejoined to other established call legs. 4.The system of claim 1 wherein the software executes directly on one ormore IP routers connected to the network.
 5. The system of claim 1wherein the software executes on one or more processors enhancing IProuters on the network.
 6. The system of claim 1 further comprising alocal area network (LAN) connecting end appliances at one or more of theIP routers, and wherein end-node legs are established via the LAN toappliances on the LAN.
 7. A method for simulating connection-orientedtelephony functions in an IP network, comprising steps of: (a)interconnecting two or more IP routers with two or more call applianceson a network; (b) setting up separate and distinct end-node call legsbetween call appliances and routers, and separate and distinctintermediate call legs between routers; and (c) joining and disjoininglegs to provide telephony functions.
 8. The method of claim 7 whereincall appliances include Interactive Voice Response (IVR) units, andwherein the system establishes end-node legs between IVRs and IProuters.
 9. The method of claim 7 comprising steps for disjoining calllegs of completed calls and maintaining one or more disjoined legs inestablished state for future use to be rejoined to other establishedcall legs in providing telephony functions.
 10. The method of claim 7wherein the software executes directly on one or more IP routersconnected to the network.
 11. The method of claim 7 wherein the softwareexecutes on one or more processors enhancing IP routers on the network.12. The method of claim 7 further comprising a local area network (LAN)connecting end appliances at one or more of the IP routers, and a stepfor establishing end-node legs via the LAN to appliances on the LAN. 13.A method for establishing an IP telephone call from a first IP-capableappliance through first and second IP routers to a second IP-capableappliance, comprising steps of: (a) setting up a separate and distinctend-node call leg between the first appliance and the first router; (b)setting up a separate and distinct end-node call leg between the secondappliance and the second router; (c) setting up at least one separateand distinct intermediate call leg between the first and second IProuters; and (d) joining the call legs to establish voice communication.14. The method of claim 13 further comprising additional interconnectedrouters and appliances, and including steps for setting up further calllegs to additional appliances and between routers, and for joining anddisjoining call legs to establish voice communication by different pathsover established call legs.
 15. The method of claim 14 wherein some calllegs are maintained after being disjoined from active calls to be usedlater to be joined to other call legs to create other active calls. 16.The method of claim 14 further comprising Interactive Voice Response(IVR) units, and wherein call legs are established to IVRs. 17.(canceled)